Semi-Closed Cube: An Effective Approach to Trading Off Data Cube Size and Query Response Time

The results of data cube will occupy huge amount ofdisk space when the base table is of a large number of attributes. Anew type of data cube, compact data cube like condensed cube andquotient cube, was proposed to solve the problem. It compresses data cubedramatically. However, its query cost is so high that it cannot be usedin most applications. This paper introduces the semi-closed cube to reducethe size of data cube and achieve almost the same queryresponse time as the data cube does. Semi-closed cube is a generalizationof condensed cube and quotient cube and is constructed from a quotientcube. When the query cost of quotient cube is higher than a giventhreshold, semi-closed cube selects some views and picks a fellow foreach of them. All the tuples of those views are materialized exceptthose closed by their fellows. To find a tuple of those views, users onlyneed to scan the view and its fellow. Thus, their query performance isimproved. Experiments were conducted using a real-world data set. Theresults show that semi-closed cube is an effective approach of datacube.